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KCET · Chemistry · Solid State

A metal crystallises in a body centred cubic lattice with the metallic radius \(\sqrt{3} \AA\). The volume of the unit cell in \(\mathrm{m}^3\) is

  1. A \(64 \times 10^{-29}\)
  2. B \(4 \times 10^{-29}\)
  3. C \(6.4 \times 10^{-29}\)
  4. D \(4 \times 10^{-10}\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(6.4 \times 10^{-29}\)

Step-by-step Solution

Detailed explanation

\(r=\sqrt{3} \AA=\sqrt{3} \times 10^{-10} \mathrm{~m}\)
For bcc,
\(\begin{aligned} & r=\frac{\sqrt{3} a}{4} \\ & a=\frac{4 r}{\sqrt{3}}=\frac{4 \times \sqrt{3} \times 10^{-10}}{\sqrt{3}}=4 \times 10^{-10} \\ & a^3=64 \times 10^{-30}=6.4 \times 10^{-29} \mathrm{~m}^3\end{aligned}\)
Thus, the volume of the unit cell is \(6.4 \times 10^{-29} \mathrm{~m}^3\).